A striking feature of the migrant caravans pulling up in Tijuana is the sheer number of children.

It's estimated they make up half of the thousands heading to the Mexican border with the United States.

Many are very young, some like Juana were born on the move. She's just one-and-a-half months old. Her parents are literally fleeing the violence of the notorious El Salvadorian gang MS13.

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Video:I handed my brother in and my life is in danger

Her mum Orlinda and dad Juan made the decision to leave everything they own behind and head to Mexico after they were told they would be murdered.

Orlinda informed on a gang member who she knew had killed two people. It was a tough decision. The gangster is her brother, and he's now serving 25 years for murder.

Image:A high proportion of the migrants are children

Such is the tragic cycle of violence in El Salvador that the brother and sister's mother was murdered in her own home by the same gangs 13 years ago.

"We are not criminals. We can't stay in our country even though we have jobs, because people like me are in danger," Orlinda tells us while sitting on a mattress in the middle of the sports gymnasium, as dozens of other migrants criss-cross around us.

Juan then describes how they were both stripped and then beaten with sticks by the gang before his brother-in-law's trial.

After sentencing, the authorities told them that they had to leave the country as they couldn't guarantee their safety.

"We're going to apply for asylum in the US because I can't be in El Salvador, I can't be in Honduras, I can't be in Guatemala," Orlinda says. "Even in Mexico I can't stay because gangs are linked with my brother's, and I handed him in and he got 25 years. My life is in danger."

The family sleeps in the gymnasium of the sports complex where the migrants are camping, but they want to move into a tent outside.

Juana is developing a respiratory illness and the doctors say that the really little children need to be in the fresh air, they say being indoors amongst so many adults is unhealthy, and can affect their tiny growing lungs.

Image:There have been protests against the presence of the migrants in Tijuana

The family said that they're fine in the camp, but are very scared about the rise in animosity towards them. A crowd of anti-migrant protesters were marching to the migrants' camp, terrifying everyone inside, before being stopped by the police.

"We were a bit scared of the protests. We were afraid the protesters would come for us, but the police told us to stay inside," the couple explains.

They dream of getting to the United States and they do have a good asylum claim, backed up by the authorities at home in El Salvador.

"We are waiting until we know what the authorities in America say," Juan tells us, "I'm taking care of my family here, just us two and the baby. I'm going to hang on until we get an answer."